Toothbrushes known to the prior art generally include a head portion and a handle portion with a common, straight line longitudinal axis. It is extremely difficult to use these straight toothbrushes to effectively clean the molars and massage the gums at the back of a user's mouth or to clean the inner sides of the teeth throughout the mouth. When a straight toothbrush is held normally in a human hand, the longitudinal axis of the brush lies at an angle approaching the vertical when the forearm of the user is horizontal. To move the longitudinal axis of the brush to a horizontal brushing position, for reaching the molars of the user, it is necessary for the wrist to pivot downwardly until the brush axis is horizontal, and then the wrist must be pivoted about a vertical axis to bring the head portion of the brush to the angle necessary to reach the molars. With the wrist in this awkward position, it is virtually impossible to manipulate the toothbrush effectively to clean the molars and massage the gums at the rear of a user's mouth.
As an alternative to wrist manipulation, most users of straight toothbrushes raise the elbow to substantially mouth level so that the brush may reach the molars. This position discourages effective brushing, as arm fatigue tends to cut short the brushing period.
Straight toothbrushes become extremely awkward when used to clean the inner surfaces of the teeth. When the toothbrush is inserted vertically from above to reach the inner surfaces of the lower incisors, the user's nose presents an obstacle to effective brushing.
To clean the rear surfaces of the molars with a straight toothbrush is extremely difficult, as the brush handle tends to contact the incisors, thus preventing the brush from reaching all rear surfaces of the molars.
In an attempt to overcome the difficulties experienced with straight toothbrushes, various angled toothbrushes have been developed to enhance the effectiveness of a toothbrushing operation. Although these angled toothbrushes have alleviated to some extent the deficiencies of straight toothbrushes, they have not been properly dimensioned or structured to be completely effective.
For example, a major structural deficiency of the known angled toothbrushes is that the brush portion is angled at a point very close to the juncture with the hand held handle portion. This requires that both the straight and angled portions of the toothbrush be inserted into the mouth to reach the rear molars, thereby increasing the awkwardness experienced in cleaning these molars. For effective operation, applicant has found that the apex of the angle between the handle and brush portions of the toothbrush should preferably remain outwardly of a user's lips during all brushing operations and should never be required to be inserted substantially within the mouth where it can contact the teeth, gums or walls of the oral cavity to inhibit movement of the brush. If this apex at the juncture between the handle and brush portions can be used as a fulcrum in the area of a user's lips for the internal movement of the brush section, the teeth may be cleaned with greater efficiency and ease.
Previously known angled toothbrushes do not take into account the very limited working areas available within the oral cavity and consequently do not provide a connecting stem between the brush and handle which is significantly reduced in size to provide ease in positioning and moving the brush. It is extremely beneficial to have the wide handle portion of the toothbrush remain externally of the oral cavity, to have the brush capable of reaching the rear molars without requiring extreme wrist and arm manipulation, and to have the brush and handle portions joined by an elongated stem of minimal width to enhance the maneuverability of the brush.
Some attempts have been made to develop angled toothbrushes with a head section which is pivotal relative to a handle section. Not only are such brushes difficult to clean, but additionally it is necessary to minimize the distance between the pivot point and the brush to prevent undesirable pivoting of the brush. The leverage action provided by a long connecting stem exerts forces on the pivot during a brushing operation which tend to cause pivoting of the head relative to the handle.
Finally, some angled toothbrushes have been developed wherein the axis of the head portion of the brush lies in a plane which is different from the plane of the handle portion of the brush. Toothbrushes of this type do not avoid the deficiencies of straight toothbrushes, for in fact the handle and head portions of these brushes lie along a straight line. In fact, these brushes require more space within the oral cavity for the accomplishment of a brushing operation than do straight toothbrushes.